I'm not sure what you mean. Are you asking for a gcode that would check if you had the most up to date version and update if available? If so, there is nothing like that at the moment.
It would be problematic because usually the firmware updates contain some changes that may require modifications to your configuration. So at the very least you would need to read the update notes before deciding to update.
Something more automated could be worked into the DWC interface, or at least link back to the github release page and notes.
Will move to the DWC wishlist.